This invention relates to digital electronic watches and more particularly to liquid crystal display watches for digitally displaying time information.
Liquid crystal display watches available today do not employ multiplexing techniques for displaying time information. Therefore, separate binary decoders are utilized for each of the functions, i.e., hours, minutes and seconds, that are to be displayed. Thus, the complexity of the circuit of the prior art watches are directly related to the number of functions to be displayed as, therefore, is production cost.
Moreover, most of the prior art liquid crystal display watches, in a normal mode of operation, display hours and minutes information. On command by the user, for example, by depressing the stem of the watch, seconds information is displayed until the stem is released, at which time, the hours and minutes information is once again displayed. To set hours to the correct time, for example, the stem is rotated away from its neutral position to a first predetermined position and depressed. To set minutes, the stem is rotated away from its neutral position to a second predetermined position and once again depressed. Thus, to display seconds and to set hours and minutes, three separate switch functions are required by the prior art.
Furthermore, if date information is to be provided, prior art watches require a separate switch function to initiate display thereof. Also, another switch is required for setting the date. Thus, to provide for displaying and/or setting of hours, minutes, date and seconds information, prior art digital electronic wrist watches require five functional switches to be employed. Each additional switch required, increases the complexity of the watch circuit and also production cost. Because the digital watch environment is highly competitive, it is very important to maintain production cost at a minimum.
Thus, a need exists to provide a multiplexing technique for liquid crystal watches to minimize circuitry complexity.
A further need exists to reduce the number of switches required for displaying and setting of time information of liquid crystal display digital watches.